4 files changed, 36 insertions, 1 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 0efa0d6..abde58c 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,8 @@
 2011-09-26  Jason Merrill  <jason@redhat.com>
 
+	PR c++/46105
+	* typeck.c (structural_comptypes): Ignore cv-quals on typename scope.
+
 	PR c++/50508
 	* semantics.c (cxx_eval_logical_expression): Use tree_int_cst_equal
 	rather than ==.
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 955e37a..10f17bf 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -1300,7 +1300,9 @@ structural_comptypes (tree t1, tree t2, int strict)
       if (!cp_tree_equal (TYPENAME_TYPE_FULLNAME (t1),
 			  TYPENAME_TYPE_FULLNAME (t2)))
 	return false;
-      if (!same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2)))
+      /* Qualifiers don't matter on scopes.  */
+      if (!same_type_ignoring_top_level_qualifiers_p (TYPE_CONTEXT (t1),
+						      TYPE_CONTEXT (t2)))
 	return false;
       break;
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index bc362ed..32cf960 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2011-09-26  Jason Merrill  <jason@redhat.com>
 
+	PR c++/46105
+	* g++.dg/template/partial12.C: New.
+
 	PR c++/50508
 	* g++.dg/cpp0x/constexpr-typedef1.C: New.
 
diff --git a/gcc/testsuite/g++.dg/template/partial12.C b/gcc/testsuite/g++.dg/template/partial12.C
new file mode 100644
index 0000000..05a3eca
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial12.C
@@ -0,0 +1,27 @@
+// PR c++/46105
+
+template< typename T >
+struct empty { // support class is like stripped-down enable_if
+    typedef void type;
+};
+
+template< class T, typename v = void > // v is always void!
+struct element {
+    typedef typename T::value_type type;
+};
+
+template< class T > // T in deduced context, T::element_type is SFINAE:
+struct element< T, typename empty< typename T::element_type >::type > {
+    typedef typename T::element_type type;
+};
+
+template< class T >
+struct element< T const, typename empty< typename T::element_type >::type > {
+    typedef typename T::element_type const type;
+};
+
+struct has_et {
+    typedef int element_type;
+};
+
+element<has_et const>::type ip = 0;